To a solution of 8-Chloro-2-methyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole (0.075 g, 0.34 mmol) in N-methyl 2-pyrolidone (0.5 mL) was added powdered potassium hydroxide (0.095 g, 1.7 mmol) and allowed to stir for 10 min at RT. 2-methyl-5-vinyl pyrimidine (0.102 g, 0.85 mmol) was added and stirred for further at 80 deg C. 3 h. After completion (TLC), reaction mixture was diluted with water (15 mL) and extracted with ethyl acetate (3×50 mL). The organic layer was dried over anhydrous sodium sulphate and concentrated under reduced pressure. The crude was purified through column chromatography (7% MeOH:DCM in silica 100-200 mesh, Diameter of column—2.5 cm, Height of silica—approx. 5 inch) then purified through preparative TLC to get the desired compound as yellow oil (0.020 g, 13% yield). 8-Chloro-2-methyl-5-[2-(2-methyl-pyrimidin-5-yl)-ethyl]-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole (0.020 g, 0.06 mmol) was dissolved in THF (1.0 mL). A solution of oxalic acid dihydrate (0.008 g, 0.06 mmol) in THF (0.5 mL) was added and stirred for 30 min at RT, Precipitate obtained was filtered and dried to give oxalate salt as off white solid (0.008 g, 32% yield).
